In essence: Caves look like sunny fields. Night looks like day. No more squinting.
For version 1.12.2 specifically, there are a few important considerations: OptiFine Dependency : Many Fullbright packs for 1.12.2 require OptiFine minecraft 1.12.2 fullbright texture pack
A fixes this by:
: Go to Video Settings and look for "Brightness." While the slider only goes to 100%, some client-side mods allow you to toggle "Fullbright" with a hotkey. In essence: Caves look like sunny fields
🛠️ Method 1: Installing a Fullbright Resource Pack (Requires OptiFine) minecraft 1.12.2 fullbright texture pack